Heavily armed soldiers have been deployed in Burundi to quell protests against the president's bid for a third term, which sparked a coup attempt last week that was foiled.

In the Musaga neighbourhood of the capital, Bujumbura, armed soldiers faced off with hundreds of angry protesters calling on President Pierre Nkurunziza to rescind his decision to seek another term in office, which many say is unconstitutional.

An Associated Press reporter in Musaga saw two soldiers firing live rounds into a crowd of protesters, who repeatedly shouted: "Shoot us."

The soldiers are armed with machine guns and rocket-propelled grenade launchers.

There was no police presence, signalling that the army, which had previously acted as a buffer between protesters and the police, has now taken over operations against demonstrators.

No injured demonstrators were seen. The soldiers who fired the shots were then ordered to leave the front line.

"The military is shooting at us, you have seen for yourselves. They came here pushing and shoving us and also doing the same to journalists, then they shot," said protester Alfred Nsengumukiza.

Seventeen security officials, including five generals, accused over the attempted coup were charged on Saturday with attempting to destabilise public institutions, said lawyers of some of the suspects. Maj Gen Godefroid Niyombare, the former intelligence chief who announced the coup on Wednesday, remains at large.

Mr Nkurunziza, who was in Tanzania for a summit to discuss his nation's troubles when the coup attempt was announced, made his first public appearance in Bujumbura on Sunday.

On Monday protesters emerged again in three neighbourhoods of Bujumbura, including Nyakabiga and Cibitoke, despite Mr Nkurunziza urging residents to stop protesting so parliamentary elections can take place later this month.

The protests began on April 26, a day after the ruling party made Mr Nkurunziza its presidential candidate in elections set for June 26.

More than 105,000 Burundians have fled to neighbouring countries recently, according to the UN.

Burundi's president has fired his defence minister and two other cabinet ministers after the failed coup attempt, an official said.